Implantable medical devices of the type having electrical circuit components are well known in the medical arts. In one particularly common form, the implantable device comprises a pacemaker unit having an appropriate electrical power supply and related control circuitry for use in electrically stimulating a patient muscle, such as the heart. Such pacemaker units commonly include a hermetically sealed case, or housing, within which the power supply and control circuitry are protectively encased, in combination with one or more conductive pacemaker leads extending from the housing to the selected muscle structure within the patient. Feedthrough terminals on the pacemaker housing accommodate hermetically sealed passage of electrical conductors to the housing exterior for appropriate connection to the pacemaker lead or leads, typically through the use of so-called connector blocks having setscrews, or the like, for secure lead attachment. Not all connector blocks utilize setscrews. Some leads are held in place by other mechanical means, such as compression seals. The connector blocks and associated feedthrough conductors disposed externally of the pacemaker housing are commonly encased within a hermetically sealed head structure, such as an insulative head of cast epoxy, or the like.
In the past, considerable research and development activity has focused upon the design of feedthrough terminals for permitting pacing signals to be transmitted from the hermetically sealed unit housing. Similarly, significant efforts have been directed toward the design of pacemaker lead connector blocks for obtaining a secure, yet hermetically sealed, electromechanical connection to pacemaker leads. However, comparatively little attention has been directed to the design of conductors and related installation methods for electromechanically interconnecting the feedthrough terminals with the associated lead connector blocks. To the contrary, available pacemaker units have predominantly utilized elongated wires extending from the feedthrough terminals and individually shaped by bending for appropriate connection by welding, or the like, to the associated connector blocks. Unfortunately, the close working space provided in a desirably compact implantable device makes this wire bending and shaping procedure both tedious and time-consuming. Moreover, in pacemaker units having multiple feedthrough terminal conductors, significant attention and skill are required to maintain the conductor wires in sufficiently spaced array to avoid short circuit failures during pacemaker unit operation.
Until recently, there existed a significant need for improvements in devices and methods for electrically interconnecting feedthrough terminals with lead connector blocks in a heart pacemaker unit or other implantable medical device, particularly with respect to permitting the desired electrical interconnections to be made quickly and easily with multiple conductors arranged and maintained in spaced relation to prevent short circuit failures. However, this need was fulfilled by the commonly-assigned U.S. Pat. Nos. 5,282,841; 5,235,742; and 5,067,903; to Szyszkowski, the disclosures of which are fully incorporated herein by reference. As disclosed in those patents, a ribbon conductor set is provided for facilitated electrical connection of feedthrough terminals and lead connector blocks in an implantable medical device, such as a heart pacemaker unit, or the like. The ribbon conductor set comprises a plurality of conductor ribbons formed as a set in predetermined number, spacing, and geometry to extend between multiple conductors at one or more feedthrough terminals and a plurality of lead connector blocks individually associated with the feedthrough conductors. The conductor ribbons are adapted for installation as a group into a pacemaker unit, and in an orientation which accommodates relatively simple connection to the feedthrough terminals and connector blocks by spot welding, or the like.